Facilities use fire pumps to provide water to sprinkler systems in the event of a fire. The fire pumps maintain a desired level of water pressure by either boosting the water pressure of a public supply of water, or by working in conjunction with a private supply of water maintained by a facility.
Pumps come in a variety of designs and sizes. Fire pumps are generally driven either by an electric power supply or a diesel power supply. Common respective pump sizes will generate 1000 gallons per minute (gpm), 1500 gpm, 2000 gpm, 2500 gpm, and greater. For example, the National Fire Protection Agency (NFPA) specification entitled, “NFPA 20: Standard for the Installation of Stationary Pumps for Fire Protection,” (2003 Edition, 1 Batterymarch Park, Quincy Mass.), sets forth that fire pumps can have ratings between 25 gpm and 5000 gpm at set flow capacities (e.g., 25 gpm, 50 gpm, 100 gpm . . . 4000 gpm, 4500 gpm, 5000 gpm). The pressure of different pumps can likewise vary. For example, the minimum pump rating set forth in NFPA 20 is 40 pounds per square inch (psi), but there is no maximum pressure. A manufacturer will design the pump to perform at a “rated” flow, pressure and speed.
In addition, a manufacturer will ensure that the fire pump satisfies a so-called standard curve. The standard curve mandates that the pump at least: (a) perform at a certain percent of the rated pressure when there is zero flow being emitted from the pump (know as a “churn” state) (for example, as per NFPA 20, churn pressure can be any pressure between 100% and 140% of rated pressure); (b) perform at 100 percent of the rated flow at 100 percent of the rated pressure; and (c) perform at 150 percent of the rated flow at 65 percent of the rated pressure. The standard curve can therefore be characterized by these three data points. In addition, a manufacturer will furnish a detailed manufacturer's curve, which identifies the specific performance of the fire pump. That is, the actual pump supplied to a customer may exceed the baseline requirements of the standard curve in various respects, which are identified by the manufacturer's curve.
Because fire pumps often protect resources of considerable value, the fire pumps are periodically performance-tested to make sure that they are working properly. A thorough acceptance test is first performed on a fire pump when it is installed in a facility. The fire pump is thereafter performance-tested on an annual basis to make sure that it continues to operate properly. The annual tests will entail assessing the fire pump's performance at three points of operation defined by the standard curve. Namely, a first test will operate the fire pump at zero flow and at a certain percentage of the rated pressure; a second test will operate the fire pump at about 100 percent of the rated flow which should optimally achieve at least 100 percent of the rated pressure; and a third test will operate the pump at about 150 percent of the flow which should optimally achieve at least 65 percent of the rated pressure. Various measurements are taken at these three points of operation to collect test data. The performance of the pump is then assessed by relying on a human to manually compare the test data to the pump's expected performance. As mentioned above, the expected performance of the fire pump is reflected by the standard curve, or more preferably, by the manufacturer's curve (if it exists). Pumps may fail (or generally degrade in performance) for any number of reasons, such as friction-related wear of the bearings, wear of the impeller or casing used in the fire pump, obstructions in the pump casing, shaft misalignment, worn wear rings, and so forth.
However, the above-described manual technique of analyzing test data can lead to erroneous results. For instance, even a skilled evaluator may fail to recognize certain problems with the fire pump (as assessed against its expected performance). These errors can result when the evaluator misreads the test data. But a more pervasive problem is due to the general difficultly in consistently making accurate pass-fail type decisions, which characterize the often complex and multi-faceted behavior of the pump. These errors can result in assessing the pump's performance as satisfactory, when it really should be graded as unsatisfactory. Or the errors may result in assessing the pump's performance as unsatisfactory, when it really should be graded as satisfactory. The former case is obviously of substantial concern, as the poor performance of a fire pump in the event of an actual fire can lead to significant loss of resources in a facility.
There is accordingly a need in the art to provide more reliable and convenient tools for assessing the performance of fire pumps. While the following disclosure is directed to the concrete examples of fire pumps, the solutions presented herein can also be applied to other kinds of pumps. Moreover, while the following disclosure is framed in the specific contexts of standards applicable to pumps deployed in the United States, the solutions presented herein can also be applied to pumps manufactured and deployed in foreign countries, with appropriate modification of relevant parameters.